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Posted: 12/5/2013 11:58:20 AM EDT
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Hey let me start by saying I hope I'm just a dumbass and doing something stupid. I'm assembling a new lower, a billet purchased on Black Friday. I'd rather not name the company at this point, again hoping I'm doing something wrong and it's not the lower. If that info is needed I may change my mind in a couple days. For now I emailed the company several days ago with no response and emailed their account here as well and am hoping to hear back from them. While assembling the lower I installed a Spikes Tactical LPK. The Mag catch won't function with PMags, tried several. The PMags simply fall back out. This is without the upper on it. I tried installing the catch as loose as I could to as tight as I could and everything in between. Hoping it was the parts I took the Daniel Defense parts out of another of my rifles and installed them in the lower. Same problem, same tests from very loose to very tight. PMags not secured at all and fall right out. These are Gen 2 Pmags. Metal GI Mags work fine in the lower. Is this something I'm doing wrong or could the lower be messed up? I have read reviews on here about this billet lower and other members didn't have the same problem with PMags. Waiting to hear back from the company but want to make sure I'm not being an idiot in the mean time. Thanks for any offered help. Also I found that if I put pressure on the end of the mag catch while its installed it secures the PMags. Without me applying the pressure though the mags fall back out. Thanks again. Edit for better spacing |
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Cam upper open, and see if you can lock a mag in place. If you can then, proceed. If not, then pull the mag catch, double check the bolt catch receiver slots for burs/clean such up if needed, and reinstall the mag catch with the threaded tip section of the mag catch flush with the face of the mag catch button. Also, don't forget to lube the parts before reinstalling them. Now try to lock the mag again with the upper open. If you can lock the mag in the well, then proceed to the next step. If not, the take a look up in to the mag, and see how much the mag lock is protuding into the mag well. On some receivers, the slot for the catch may be a tad under milled, or on the catch, the flat that mates up to the receiver to limit how far in the catch will protrude, under milled as well. If we are good now, then proceed to the next step.
From here, lock the upper back in place, lock the bolt back, and look straight up the front inside of the mag well from the lower, to the upper receiver. Is the mating of the two surfaces flush, or does the upper receiver front edge protrude over the surface line of the lower receiver (read they should both be on the same plane). Next if the lower and upper surfaces are on the same plane , disassemble the mag, and with just the body alone, and the bolt locked home, see if you can get the mag to lock home. Here, we are seeing if the lips of the mag are bottoming out against the bottom of the bolt before the mag can lock home. If the mag lips bottom out on the the bottom of the carrier before the mag will seat home, then either then it might come down to either having the receiver replace, or to mod the mag catch locking edge to gain the needed clearance. If you are good to go so far, then down load a mag by a few rounds, and with the bolt closed home, install a mag in the well, then use the palm of you hand to slap upwards on the mag to drive it home. Lastly, although some mag bodies are 30 rounders, the anti tilt follower will take up some room in a mag. A mag is fully loaded with the top round still can be compressed down into the mag around 2/3 of the way to allow another round to be loaded. This space still left in the mag is needed since when a fully loaded mag is loaded into the rifle with the bolt locked home, the stack of rounds have to be able to be driving downward in the mag about 1/2 of a round space so the mag can lock in place. As the bolt comes back, the round stack moves upwards in front of the bolt, and allows for the bolt to cleanly strip a round out. |
| I do appreciate the help. All of this is without the upper installed. I'm guessing the mag catch is not reaching far enough into the mag well. I don't see any burs or anything so I can only guess it wasn't milled deep enough. Guess I will wait and see what the company says. Thanks again. |
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Quoted:
I do appreciate the help. All of this is without the upper installed. I'm guessing the mag catch is not reaching far enough into the mag well. I don't see any burs or anything so I can only guess it wasn't milled deep enough. Guess I will wait and see what the company says. Thanks again. Sounds more likely that the magazine catch location wasn't milled correctly in the lower. If the catch was positioned slightly too high, a PMag would not be able to be inserted far enough to reach the catch, but USGI metal mags, which don't have an overtravel stop, could if no upper is attached. |
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I thought that too but like I said I tested putting pressure on the end of the mag catch pushing the end in towards the mag well while installed and it caught the PMag with the pressure applied. I was wondering if an angle might be off or something or if it is just not milled deep enough. Maybe I'm crazy, I don't know at this point. Maybe I should make a short youtube video to show what's happening. ETA - Just heard from the manufacturer. They say it is done to Colt specs and is possibly due to out of spec parts. Apparently some other people have had the same issue. Regardless they have offered to mill it out further and said all future lowers are going to be milled a little further to avoid this problem. Only bummer is a timeline of about a month to get my lower back. Thanks again everybody, will let you know how it all pans out.
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| Yeah using the spring that came with the kit. And as mentioned I also tested with a Daniel Defense kit. You're right though. Is it possible the spring is getting far enough in or something? I'm going to mess with it further after dinner. Thanks. Also it's not like I'm able to noticeably bend the mag catch it's just that with pressure applied it to it it works so I'm guessing whatever the situation it's not a huge difference, just enough to be a problem. |
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Quoted:
canned response ? lol would make sense to have them saved somewhere Not a canned response. It just seems that way since you may read close to the same response over and over again over the decade that I have been mod't this forum for the same problem that arises over and over again. _________________________________________________ CJohnson40, the fact that mag catches do not really wear out, choices sounds like its coming down to sending the receiver back to have the catch bridge channel deepened a touch, or if you have someone local with a mill (carbine end mill), might be faster to just mill the catch instead. 
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The problem is probably a combination of the billet lower's magazine opening, and the stop on the PMags.
PMags can vary a little dimensionally. And, the magazine opening on many billet lowers is not the same on fogred lowers, and there is probably some conflict between the bottom of the lower, and the travel stop molded onto the outside of the PMag. Take a PMag and slide it up into the lower receiver. Watch the way the PMag travel stop limits how far the magazine can be inserted into the Lower. My guess is that the travel stop is hitting the bottom edge of the lower receiver's magazine opening, preventing the PMag from locking into the lower. That's mostly a problem with design and manufacturing of the lower. And, yeah, GI mags are slab sided without the travelstop, so they would still work fine on a lower with this problem. Some PMags won't lock onto a standard forge lower because of the same problem. The answer for you is to take a file to the downstop on your PMags and take enough off the travel stop so that there is a slight gap between the bottom of the magazine opening, and the travel stop on the PMags. You need a clearnce gap so you can shove PMags in past the magazine catch so they can lock on. While this is the solution for your PMags, it means that you might have a problem if you ever borrow a PMag from someone else. The only answer to that would be to take a file to the bottom of your receiver and file until a fresh PMag will reliably lock in, OR send the lower back to the manufacturer to have the magazine opening enlarged, and the lower refinished. |
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Quoted: The problem is probably a combination of the billet lower's magazine opening, and the stop on the PMags. Quoted: The problem is probably a combination of the billet lower's magazine opening, and the stop on the PMags. I did check that. The edge of the PMags don't prevent it from going high enough. I checked it with the mag catch out to make sure that wasn't happening. As far as being secretive I just wanted to make sure I wasn't messing things up myself and potentially causing problems for a company who didn't deserve it. At this point they've agreed to fix it so I'm comfortable saying it was a Spartan lower from Joe Bobs. Again I have no complaints at this point as they are agreeing to make it right and I love the lower in every other regard. Plus the price was more than right. Thanks again guys. |
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